雨果是一个小大脚怪，波恩是一个小男孩。在一次不太可能发生的邂逅之后，他们成为了一对更令人意想不到的好朋友。在存够了他的怪物卡包装纸后，雨果邮购了一件特别的奖品——怪物探测器！使用这个类似手表的装置，雨果很快就在自己的洞穴里发现了一只怪物。雨果被吓坏了，他前往学校，发现了另一个惊喜——他的朋友布恩！布恩宣布他想去大脚野人学校上学，但以前从来没有人类在这里上过学，而且不是每个人都像雨果那样高兴。布恩上学的**天就遇到了困难，但雨果没有太多时间担心，后来他又看到了一个怪物，并开始追赶它。接下来是更多的惊喜，这些惊喜让雨果和布恩重新思考"怪物"的真正含义。

Hugo is a young Sasquatch. Boone is a young boy. After an unlikely encounter, they’ve become an even unlikelier pair of best friends. After saving up his Monster Card wrappers, Hugo sends away for a special prize in the mail—a Monster Detector! Using the watchlike device, Hugo quickly spots a monster right in his own cavern. Spooked, Hugo heads to school and finds yet another surprise—his friend Boone! Boone announces he wants to go to Sasquatch school, but no human has ever gone before, and not everyone is as happy about it as Hugo. Boone’s first day of school gets off to a rocky start, but Hugo doesn’t have much time to worry before he makes another monster sighting and takes off after the creature. What follows are even more surprises, ones that have Hugo and Boone rethinking what it really means to be a “monster.”